The invention relates to an apparatus for cooling gases, especially in the exhaust tract of an internal combustion engine.
It is know, for example, to cool a hot gas through a special configuration of the gas pipexe2x80x94made of metal, as a rulexe2x80x94or by mixing of the gas with a cooler medium.
The invention is addressed to the problem of constructing a device for cooling gases in such a way that it is possible to arrange it in a simple manner in already existing cooling systems.
The apparatus of the invention, of the kind stated in the beginning, is advantageously configured such that the gas can be carried through channels in a cooling device, channels for a flowing coolant medium also being present in the cooling device in the neighborhood of the channels for the gas. It is thus possible in a simple manner to integrate the cooling device for the gas in an already existing coolant circuit bearing a corresponding coolant which, as a rule, is a liquid.
To achieve good heat removal, the cooling device has the channels for the coolant centered inside of it and, radially on its exterior, the channels for the gas to be cooled, while it has cooling fins on its exterior for further improvement of heat removal.
In a preferred embodiment the gas is branched off from the exhaust gases of an internal combustion engine and is returned into the air intake tract of the internal combustion engine (so-called exhaust gas returnxe2x80x94EGR) and the cooling medium is the coolant in the coolant circuit of the internal combustion engine.
The cooling device of the invention can be produced advantageously by making the cooling device with the channels from pressure-cast parts, a first cover being present with an annular inlet for the gas being cooled and a second cover with a funnel-shaped outlet for the gas being cooled. With the annular inlet an especially uniform distribution in the channels of the cooling device when it flows in is made possible, and with the funnel-shaped outlet a uniform passage through the channels can be achieved.
Furthermore, in this embodiment a middle piece is present between the covers with the channels, so that one set of channels in the cooling device permits the gas to flow through them and the other set of channels permits the cooling medium to flow in alternating directions, while an extruded aluminum profile bearing the cooling fins is advantageously mounted externally on the middle piece.
Preferably, three channels for the coolant are formed by radial dividing walls inside of the cooling device, and externally six channels for the gas being cooled are likewise formed by radial dividing walls.